/**** 
* Plugins
****/ 
var tween = LK.import("@upit/tween.v1");

/**** 
* Classes
****/ 
var Bird = Container.expand(function () {
	var self = Container.call(this);
	var birdGraphics = self.attachAsset('bird', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.xSpeed = 10.9375;
	self.ySpeed = -20;
	self.gravity = 1;
	self.lift = -15;
	self.flap = function () {
		self.ySpeed = self.lift * 1.5;
		LK.getSound('flap').play();
	};
	self._update_migrated = function () {
		if (game.isMouseDown) {
			self.ySpeed += self.gravity / 3;
		} else {
			self.ySpeed += self.gravity;
		}
		self.y += self.ySpeed;
		self.x += self.xSpeed;
		if (self.y <= 0 || self.y >= 2732) {
			self.speed = -self.speed;
		}
		var targetRotation = Math.atan2(self.ySpeed, self.xSpeed * self.scale.x) / 2;
		birdGraphics.rotation += (targetRotation - birdGraphics.rotation) / 10;
	};
	self.flip = function () {
		self.scale.x *= -1;
	};
});
var Obstacle = Container.expand(function () {
	var self = Container.call(this);
	var obstacleShadow = self.attachAsset('obstacleShadow', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	obstacleShadow.rotation = Math.PI / 4;
	var obstacleShadow2 = self.attachAsset('obstacleShadow2', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	obstacleShadow2.rotation = Math.PI / 4;
	obstacleShadow2.y = -7;
	var obstacleGraphics = self.attachAsset('obstacle', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	obstacleGraphics.rotation = Math.PI / 4;
	self.speed = 5;
	self._move_migrated = function (speed) {
		self.y += speed;
	};
});
var Wall = Container.expand(function () {
	var self = Container.call(this);
	var wallGraphics = self.attachAsset('wall', {
		anchorX: 0.5,
		anchorY: 0.5
	});
});

/**** 
* Initialize Game
****/ 
var game = new LK.Game({
	backgroundColor: 0x000000
});

/**** 
* Game Code
****/ 
var tutorialTextWhite = new Text2('Tap to Flap\nHold to Float', {
	size: 150,
	fill: '#ffffff',
	font: 'Impact',
	align: 'center'
});
tutorialTextWhite.anchor.set(.5, 1);
tutorialTextWhite.x = -4;
tutorialTextWhite.y = -62;
LK.gui.bottom.addChild(tutorialTextWhite);
var tutorialText = new Text2('Tap to Flap\nHold to Float', {
	size: 150,
	fill: '#3a84f7',
	font: 'Impact',
	dropShadow: true,
	dropShadowColor: '#222a9a',
	dropShadowBlur: 5,
	dropShadowDistance: 7,
	dropShadowAngle: 0,
	align: 'center'
});
tutorialText.anchor.set(.5, 1);
tutorialText.y = -50;
LK.gui.bottom.addChild(tutorialText);
game.score = 0;
game.obstacleSpeed = 5;
game.obstacleSpeedIncrease = 0.005;
game.maxHealth = 100;
game.currentHealth = 100;
game.speedBoostTimer = 0;
game.speedBoostDuration = 0;
game.isSpeedBoosted = false;
game.baseObstacleSpeed = 5;
game.currentSpeed = 5;
game.targetSpeed = 5;
game.speedTweenTimer = 0;
game.checkObstacleCollision = function (obstacles) {
	for (var i = 0; i < obstacles.length; i++) {
		obstacles[i]._move_migrated();
		var dist = Math.sqrt(Math.pow(bird.x - obstacles[i].x, 2) + Math.pow(bird.y - obstacles[i].y, 2));
		if (dist < 200) {
			game.currentHealth -= 20;
			LK.getSound('bounce').play();
			obstacles[i].destroy();
			obstacles.splice(i, 1);
			if (game.currentHealth <= 0) {
				LK.setScore(game.score);
				LK.getSound('gameOverJingle').play();
				LK.showGameOver();
			}
			break;
		}
	}
};
game.setBackgroundColor(0xadd8e6);
var scoreText = new Text2('0', {
	size: 150,
	fill: '#3a84f7',
	font: 'Impact',
	dropShadow: true,
	dropShadowColor: '#222a9a',
	dropShadowBlur: 5,
	dropShadowDistance: 7,
	dropShadowAngle: 0
});
scoreText.anchor.set(.5, 0);
LK.gui.top.addChild(scoreText);
var scoreText2 = new Text2('0', {
	size: 150,
	fill: '#ffffff',
	font: 'Impact'
});
scoreText2.anchor.set(.5, 0);
scoreText2.x = -4;
scoreText2.y = -5;
LK.gui.top.addChild(scoreText2);
LK.gui.top.addChild(scoreText);
// Health bar background
var healthBarBg = new Text2('████████████████████', {
	size: 60,
	fill: '#444444',
	font: 'Impact'
});
healthBarBg.anchor.set(0, 0);
healthBarBg.x = 120;
healthBarBg.y = 20;
LK.gui.topLeft.addChild(healthBarBg);
// Health bar fill
var healthBarFill = new Text2('████████████████████', {
	size: 60,
	fill: '#00ff00',
	font: 'Impact'
});
healthBarFill.anchor.set(0, 0);
healthBarFill.x = 120;
healthBarFill.y = 20;
LK.gui.topLeft.addChild(healthBarFill);
// Health text
var healthText = new Text2('HP', {
	size: 60,
	fill: '#ffffff',
	font: 'Impact'
});
healthText.anchor.set(0, 0);
healthText.x = 120;
healthText.y = 80;
LK.gui.topLeft.addChild(healthText);
var bird = game.addChild(new Bird());
var leftWall = game.addChild(new Wall());
leftWall.x = 0;
leftWall.y = 1366;
var rightWall = game.addChild(new Wall());
rightWall.x = 2048;
rightWall.y = 1366;
var leftObstacles = [],
	rightObstacles = [],
	bottomObstacles = [];
var bottomObstacleSpawnTime = Math.floor(Math.random() * obstacleSpawnRandomness) + obstacleSpawnRandomness * 2;
var obstacleSpawnRandomness = 120;
var obstacleSpawnRandomnessDecrease = 0.025 * (2 / 3);
var obstacleSpawnY = -500;
var leftObstacleSpawnTime = Math.floor(Math.random() * obstacleSpawnRandomness) + obstacleSpawnRandomness;
var rightObstacleSpawnTime = Math.floor(Math.random() * obstacleSpawnRandomness) + obstacleSpawnRandomness;
bird.x = 1024;
bird.y = 1366;
game.isMouseDown = false;
game.isZeroPressed = false;
game.down = function (x, y, obj) {
	bird.flap();
	game.isMouseDown = true;
};
game.up = function (x, y, obj) {
	game.isMouseDown = false;
};
game.keydown = function (key) {
	if (key === '0') {
		game.isZeroPressed = true;
		game.score++;
		LK.setScore(game.score);
		scoreText.setText(game.score);
		scoreText2.setText(game.score);
	}
};
game.keyup = function (key) {
	if (key === '0') {
		game.isZeroPressed = false;
	}
};
game.update = function () {
	bird._update_migrated();
	if (game.isMouseDown && LK.ticks % 15 === 0) {
		bird.flap();
	}
	if (game.isZeroPressed && LK.ticks % 10 === 0) {
		game.score++;
		LK.setScore(game.score);
	}
	if (game.score > 2) {
		tutorialText.y += 5;
		tutorialTextWhite.y += 5;
	}
	scoreText.setText(game.score);
	scoreText2.setText(game.score);
	// Update health bar
	var healthPercentage = game.currentHealth / game.maxHealth;
	var healthBarLength = Math.floor(20 * healthPercentage);
	var healthBarText = '';
	for (var h = 0; h < healthBarLength; h++) {
		healthBarText += '█';
	}
	healthBarFill.setText(healthBarText);
	// Change health bar color based on health level
	if (healthPercentage > 0.6) {
		healthBarFill = new Text2(healthBarText, {
			size: 60,
			fill: '#00ff00',
			font: 'Impact'
		});
	} else if (healthPercentage > 0.3) {
		healthBarFill = new Text2(healthBarText, {
			size: 60,
			fill: '#ffff00',
			font: 'Impact'
		});
	} else {
		healthBarFill = new Text2(healthBarText, {
			size: 60,
			fill: '#ff0000',
			font: 'Impact'
		});
	}
	healthBarFill.anchor.set(0, 0);
	healthBarFill.x = 120;
	healthBarFill.y = 20;
	LK.gui.topLeft.addChild(healthBarFill);
	game.obstacleSpeed += game.obstacleSpeedIncrease;
	// Speed tween system - change speed every 5 seconds (300 ticks at 60fps)
	if (LK.ticks - game.speedTweenTimer >= 300) {
		game.speedTweenTimer = LK.ticks;
		// Set new target speed with visible variation (±30% of base speed)
		var speedVariation = 0.7 + Math.random() * 0.6; // 0.7x to 1.3x speed multiplier
		game.targetSpeed = game.baseObstacleSpeed * speedVariation;
		// Tween to new speed over 1 second
		tween(game, {
			currentSpeed: game.targetSpeed
		}, {
			duration: 1000,
			easing: tween.easeInOut
		});
	}
	// Use current tweened speed for obstacles
	game.obstacleSpeed = game.currentSpeed;
	obstacleSpawnRandomness -= obstacleSpawnRandomnessDecrease;
	if (obstacleSpawnRandomness < 20) {
		obstacleSpawnRandomness = 20;
	}
	if (LK.ticks >= leftObstacleSpawnTime) {
		var newObstacle = game.addChildAt(new Obstacle(), 0);
		newObstacle.x = Math.random() * (2048 - 600) + 300; // Random x position with margins
		newObstacle.y = obstacleSpawnY;
		leftObstacles.push(newObstacle);
		leftObstacleSpawnTime += Math.floor(Math.random() * obstacleSpawnRandomness) + obstacleSpawnRandomness;
	}
	if (LK.ticks >= rightObstacleSpawnTime) {
		var newObstacle = game.addChildAt(new Obstacle(), 0);
		newObstacle.x = Math.random() * (2048 - 600) + 300; // Random x position with margins
		newObstacle.y = obstacleSpawnY;
		rightObstacles.push(newObstacle);
		rightObstacleSpawnTime += Math.floor(Math.random() * obstacleSpawnRandomness) + obstacleSpawnRandomness;
	}
	if (bird.intersects(leftWall) && bird.xSpeed < 0 || bird.intersects(rightWall) && bird.xSpeed > 0) {
		bird.xSpeed = -bird.xSpeed;
		bird.flip();
		game.score++;
		LK.setScore(game.score);
		LK.getSound('bounce').play();
	}
	for (var i = leftObstacles.length - 1; i >= 0; i--) {
		leftObstacles[i]._move_migrated(game.obstacleSpeed);
		if (leftObstacles[i].y > 3232) {
			leftObstacles[i].destroy();
			leftObstacles.splice(i, 1);
		}
	}
	for (var i = rightObstacles.length - 1; i >= 0; i--) {
		rightObstacles[i]._move_migrated(game.obstacleSpeed);
		if (rightObstacles[i].y > 3232) {
			rightObstacles[i].destroy();
			rightObstacles.splice(i, 1);
		}
	}
	if (LK.ticks >= bottomObstacleSpawnTime) {
		var newObstacle = game.addChildAt(new Obstacle(), 0);
		newObstacle.x = Math.random() * (2048 - 600) + 300; // Random x position with margins
		newObstacle.y = 2732 + 300; // Start below screen
		bottomObstacles.push(newObstacle);
		bottomObstacleSpawnTime += Math.floor(Math.random() * obstacleSpawnRandomness) + obstacleSpawnRandomness * 1.5;
	}
	for (var i = bottomObstacles.length - 1; i >= 0; i--) {
		bottomObstacles[i]._move_migrated(-game.obstacleSpeed); // Move upward (negative speed)
		if (bottomObstacles[i].y < -500) {
			bottomObstacles[i].destroy();
			bottomObstacles.splice(i, 1);
		}
	}
	game.checkObstacleCollision(leftObstacles);
	game.checkObstacleCollision(rightObstacles);
	game.checkObstacleCollision(bottomObstacles);
	if (bird.y < 0 || bird.y > 2732) {
		LK.setScore(game.score);
		LK.getSound('gameOverJingle').play();
		LK.showGameOver();
	}
};

===================================================================
--- original.js
+++ change.js
@@ -1,5 +1,10 @@
 /**** 
+* Plugins
+****/ 
+var tween = LK.import("@upit/tween.v1");
+
+/**** 
 * Classes
 ****/ 
 var Bird = Container.expand(function () {
 	var self = Container.call(this);
@@ -106,8 +111,11 @@
 game.speedBoostTimer = 0;
 game.speedBoostDuration = 0;
 game.isSpeedBoosted = false;
 game.baseObstacleSpeed = 5;
+game.currentSpeed = 5;
+game.targetSpeed = 5;
+game.speedTweenTimer = 0;
 game.checkObstacleCollision = function (obstacles) {
 	for (var i = 0; i < obstacles.length; i++) {
 		obstacles[i]._move_migrated();
 		var dist = Math.sqrt(Math.pow(bird.x - obstacles[i].x, 2) + Math.pow(bird.y - obstacles[i].y, 2));
@@ -266,26 +274,24 @@
 	healthBarFill.x = 120;
 	healthBarFill.y = 20;
 	LK.gui.topLeft.addChild(healthBarFill);
 	game.obstacleSpeed += game.obstacleSpeedIncrease;
-	// Random speed boost system
-	if (!game.isSpeedBoosted && Math.random() < 0.001) {
-		// 0.1% chance per frame for speed boost
-		game.isSpeedBoosted = true;
-		game.speedBoostTimer = LK.ticks;
-		game.speedBoostDuration = Math.random() * 300 + 120; // 2-7 seconds at 60fps
-		game.baseObstacleSpeed = game.obstacleSpeed;
+	// Speed tween system - change speed every 5 seconds (300 ticks at 60fps)
+	if (LK.ticks - game.speedTweenTimer >= 300) {
+		game.speedTweenTimer = LK.ticks;
+		// Set new target speed with visible variation (±30% of base speed)
+		var speedVariation = 0.7 + Math.random() * 0.6; // 0.7x to 1.3x speed multiplier
+		game.targetSpeed = game.baseObstacleSpeed * speedVariation;
+		// Tween to new speed over 1 second
+		tween(game, {
+			currentSpeed: game.targetSpeed
+		}, {
+			duration: 1000,
+			easing: tween.easeInOut
+		});
 	}
-	// Apply speed boost
-	if (game.isSpeedBoosted) {
-		var boostMultiplier = 1.3 + Math.random() * 0.4; // 1.3x to 1.7x speed boost
-		game.obstacleSpeed = game.baseObstacleSpeed * boostMultiplier;
-		// End speed boost after duration
-		if (LK.ticks - game.speedBoostTimer > game.speedBoostDuration) {
-			game.isSpeedBoosted = false;
-			game.obstacleSpeed = game.baseObstacleSpeed;
-		}
-	}
+	// Use current tweened speed for obstacles
+	game.obstacleSpeed = game.currentSpeed;
 	obstacleSpawnRandomness -= obstacleSpawnRandomnessDecrease;
 	if (obstacleSpawnRandomness < 20) {
 		obstacleSpawnRandomness = 20;
 	}